The 1990 meeting will be the continuation of a very successful meeting series on the molecular biology of hepatitis B viruses started in 1985. As in the past years sessions will be devoted to the replication of the hepadnavirus genome, the biosynthesis of viral proteins, the mechanisms and control of viral transcription, the structure and assembly of virus particles, the natural history of viral infection in vivo, the role of hepadnaviruses in the formation of liver cancer and the development and strategies for antiviral therapies. Each session will consist of 10 minute presentations selected from therapies. Each session will consist of 10 minute presentations selected from submitted abstracts, followed by a 5 minute discussion period. Sessions will be chaired by knowledgable scientists actively engaged hepadnavirus research. The function of the chairman is to provide a brief overview of each area and to stimulate the discussion among the conferees. Additional abstracts will be presented in two poster sessions. Chronic hepatitis B virus infection is a major cause of cirrhosis, liver failure and liver cancer. A better understanding of the molecular aspects of hepatitis B virus infection is a vital prerequisite for the development of effective antiviral therapies and thus for the prevention of HBV induced disease. The identification of animal models for HBV infection and the possibility to express infectious hepadnaviruses in tissue culture cells resulted in a rapid increase in the number of informative investigations concerning the represented topics. The need from workers in the field to keep abreast of these advances certainly justifies the continuation of this series of meetings in 1990.